Protector structure for gas mask exhalation valves



Nov. 23, 1954 M. GLIDDEN PROTECTOR STRUCTURE FOR' GAS MASK EXHALATION VALVES Filed May 16, 1952 1N VEN TOR.

ATTORNEYS.

United States Patent PROTECTOR STRUCTURE FOR GAS MASK EXHALATION VALVES Gaien M. Glidden, Wheaten, Iil., assignor to Acme Protic tion Equipment Company, Chicago, 111., a partner- 5 ip Application May 16, 1952, Serial No. 288,146

8 Claims. (Cl. 128141) This invention relates to a protector structure for gas mask exhalation valves. Gas masks equipped with the protector structure of this invention are admirably adapted for use at very low temperatures, and also for use in rubber solvent atmospheres.

Both, military and industrial gas masks include face pieces adapted to conform to the face of the wearer and to provide an enclosed air chamber about the nose and mouth of the wearer into which air is drawn by the decrease in pressure within the mask upon the inhalation of air from the enclosed space by the wearer, and from which air is discharged by the increase in pressure within the enclosed space due to the exhalation of the wearer. To provide for the exhausting of the air from the face piece, it is equipped with an exhalation outlet controlled by an exhalation valve. The structure of the exhalation valve must be such as to make possible the ejection of air from the face piece with a minimum of effort by the wearer, while at the same time completely preventing leakage of air from the atmosphere into the face piece. It is the general practice to employ check valve means for this purpose having flexible, resilient valve elements which normally are in sealing contact, but open automatically in proportion to the increase of pressure within the face piece for the discharge of air therefrom. Flutter-type valves and diaphragm-type valves are most commonly employed, since their actions correspond to the requirements just discussed.

The functioning of exhalation valves presents a difficult problem when it is desired to use gas masks at temperatures below 32 F., and especially at temperatures below 0 F. The warm air exhaled from the face piece contains a considerable amount of moisture. The rapid cooling of this air as it is discharged to the atmosphere through the exhalation valve increases its relative humidity, and causes moisture to condense in the exhalation outlet and on the valve elements. At subfreezing temperatures this condensed moisture forms a frothy type of ice, which is known as rime ice. Rime ice has a relatively large volume for the amount of water contained therein because of the presence of a large number of air bubbles. Thus, the formation of even a small amount of rime ice on the exhalation valve elements tends to seriously impair the functioning of the exhalation valve. Under very cold conditions, say below 0 C., it is common for the exhalation valve to freeze in either an open or closed position, which therefore demands immediate action to put the valve back into service. Also, the accumulation of ice on the valve elements tends to produce an undesirable leakage from the atmosphere into the face piece. Some efforts have been made to overcome these problems and to improve the operation of gas mask exhalation valves at low temperatures, but heretofore no satisfactory means has been developed for maintaining the proper functioning of exhalation valves at temperatures below 30 F.

It is therefore a general object of this invention to provide a protector structure for gas mask exhalation valves to adapt gas masks for use at subfreezing temperatures. More particularly, it is an object of this invention to equip gas masks with means for preventing the formation of ice on the exhalation valve elements. It is a further object of this invention to provide an extension for attachment to the face pieces of gas masks in alignment with the valvecontrolled exhalation outlet providing an auxiliary check valve in series with the primary check valve to provide a warm air chamber therebetween for keeping the primary or inner check valve comparatively Warm. It is a still further object of this invention to adapt the protector ice structure so that the inner or primary valve is kept free of ice, while the outer or secondary valve is adapted to permit it to be kept in serviceable condition and freed of accumulated ice by the wearer without removing the mask. Further objects and advantages will appear as the specification-proceeds.

This invention is shown in an illustrative embodiment in the accompanying drawing, in which- Fig. 1 is a perspective view of a gas mask equipped with a protector structure constructed in accordance withthe principles of this invention; Fig. 2, a bottom view of the exhalation valve protector structure of Fig. 1 showing the parts in their normal position; Fig. 3, a bottom view similar to Fig. 2 showing the extension in flexed condition with the annular valve seat displaced from the diaphragm; Fig. 4, a partial vertical sectional view of' the inhalation and exhalation means of the mask of Fig. l; and Fig. 5, a perspective view of the main elements of the structure shown in Fig. 4 showing the parts in separated relation.

Referring now to the drawing, there is shown a gas mask designated generally at 10, and including a face portion 11 for fitting snugly over the face of the wearer. The face portion may be provided with a plurality of buckles 12 for receiving straps 13 for securing the face portion to the face of the wearer. The gas mask is also provided with a pair of lenses or windows 14 which are held in place in the face portion 11 by means of rims 15. The face portion 11 of the gas mask may be suitably moulded from rubber or other similar resilient, flexible material.

In the illustration given, face portion 11 of the gas mask is integrally formed with a tubular exhaust conduit 16 providing interiorly an exhaust outlet or passage 17. The lower end of conduit 16 is adapted to provide a flexible, annular valve seat 18. Preferably, a valve seat 18 is made convex, as shown more clearly in Fig. 4. The lower portion of conduit 16 is grooved internally at 19 and 20 so that a concentric member can be secured therein. In the illustration given, this member consists of a ring member 21 integrally connected by means of webs 22 to a tubular intake conduit 23. Web connections 22 are spaced apart to provide a plurality of passages 24 therethrough, as seen more clearly in Fig. 5. Ring 21 is provided with a pair of shoulders 25 and 26 which cooperate with grooves 19 and 20 in retaining ring 21 and thereby intake conduit 23 in centered relation with respect to exhaust conduit 16. Thus, it can be seen that the mounting of intake conduit 23 concentrically within exhaust conduit 16 causes exhaust passage 16 to assume an annular form, and that inlet passage 27 is provided with an intake conduit 23. I

A diaphragm exhalation valve 28 is mounted on intake conduit 23, as shown more clearly in Fig. 4. This is accomplished by forming diaphragm 28 out of flexible, resilient material such as rubber with a disc portion 29 and a sleeve portion 30. The sleeve portion is locked to conduit 23 by abutting against shoulder 31 and by having portions engaging ridge 30 and seating within recess 33. The disc portion 29 of diaphragm 28 is constructed with an upwardly concave peripheral portion 34, as seen more clearly in Fig. 4, so that only the outermost edge of disc portion 29 rests against valve seat 18 at equilibrium pressure, that is, when the pressure within the face piece is substantially the same as atmospheric pressure. With the diaphragm construction shown, on the reduction of pressure within the face piece by the inhalation of the wearer this portion 29 will flex inwardly, and when the pressure within the face piece is sufficiently reduced concave peripheral portion 34 will seat on the adjacent convex portion of seat 18. However, as soon as the pressure within the face piece returns to atmospheric, the resiliency of this portion 29 will cause it to snap back into the position illustrated in Fig. 4, so that only a substantially line contact is maintained between diaphragm 28 and valve seat 18.

In the illustration given, the inner end of conduit 23 is received within an integral intake conduit extension 35, as seen more clearly in Fig. 4. Thus, interiorly member 35 provides an extension of intake passage 27 leading upwardly through the interior of member 33 to a valveequipped outlet opening 36. If desired, extension 35 can While the gas mask structure just described has been found to be highly effective at temperatures above 32 F., at subfreezing temperatures, and especially at temperatures below C., it begins to give trouble due to the formation of ice on valve seat 18 and diaphragm 28. As previously indicated, the formation of ice on the exhalation valve elements may cause them to become frozen in either an open or closed position, or at the very least to cause an undesirable leakage of air from the atmosphere into the face piece. Therefore, when it is desired to use a gas mask at low temperatures, it is desirable that it be equipped with the exhalation valve protector structure, which will subsequently be described in detail.

The protector structure of this invention comprises an outward extension 37 carried by face piece 11 in alignment with exhalation outlet 17. In the illustration given, extension 37 is of tubular shape, and is provided with a reduced neck portion 38 which is received about the lower portion of conduit 16 just above annular valve seat 18, and is detachably secured thereto by means of hose clamp 39. Preferably, extension 37 is composed entirely of a resilient, flexible material such as rubber.

Extension 37 provides interiorly a chamber 40, as seen more clearly in Fig. 4, having outwardly-accessible flexible walls 41. Chamber 49 has an inlet 42 at its upper end through the upper or primary exhalation valve provided by valve seat 18 and diaphragm 28. Chamber 4G is also provided with an ontlet opening 43 at its lower end, which is also preferably valve-controlled. In the illustration given, there is integrally formed with extension 37 an inwardly-extending annular portion 44 providing an annular valve seat 45 of convex shape, similar to upper valve seat 18, and spaced from intake conduit 23 by means of a plurality of webs 46 connected to ring 47, as seen more clearly in Fig. 5. Ring 47 is adapted to be snugly received about intake conduit 23 to assist in supporting extension 37. Between Webs 46 there is provided a plurality of openings which together constitute outlet 43.

To cooperate with convex valve seat 45 there is provided a diaphragm 43, similar to diaphragm 2S. Preferably, diaphragm 48 is constructed of flexible, resilient material such as rubber and is provided with disc portion 49 and sleeve portion 56. Sleeve portion 50 is adapted to be snugly received on conduit 23 between the outer end of ring 43 and threaded attachment connection 51. Disc portion 49 is preferably equipped with an upwardlyconcave peripheral portion 52 adapted to function in the same way as peripheral portion 42 of upper diaphragm 28.

If desired, extension 37 can be extended below annular portion 44 to provide a cylindrical guard portion 52 to provide protection for diaphragm valve 48.

Operation In the operation of the exhalation valve protector structure just described, the exhaled air passes through chamber 40 and portions thereof are held up therein between periods of exhalation. Thus, the air trapped within chamber 40 will be at approximately the same temperature as the air within the face piece, and will therefore keep inner valve elements 18 and 29 comparatively warm, and free from contamination. In actual tests of a mask similar to the one shown in the drawing, it has been found that the warm exhaled air trapped between the inner and outer exhalation check valves serves to keep the inner valve in satisfactory operating condition down to temperatures of 50 F.

The outer check valve provided by valve seat 45 and diaphragm 48 is exposed on its outside to the atmosphere, and will therefore be subject to the formation of ice when the mask is used at subfreezing temperatures. However, the formation of only small amounts of ice on the outer valve elements is not particularly objectionable. The outer valve elements will continue to provide a suflicient restriction to the movement of air between chamber 40 and the atmosphere during the intervals between exhalations to keep the temperature within chamber 40 well above atmospheric temperature so that the inner valve members are kept comparatively warm. Furthermore, if the outer valve elements should become unduly stiffened due to the accumulation of ice thereon, or if diaphragm 48 should freeze tight to valve seat 45, or become frozen in an open position, the outer valve elements can be moved (Lil - inert atmosphere chamber.

relative to each other, as indicated in Fig. 3, by flexing the wall of extension 37. This operation can be quickly and conveniently accomplished by the wearer of the mask by merely grasping extension 37 by the hand and applying flexing pressure thereto. This flexing of extension 37 will serve to break the valve elements loose when they are frozen in either an open or closed position, and to free them of accumulated ice. Therefore, the outer check valve can be kept in satisfactory operating condition by the wearer even at extremely low temperatures by the 1expedient of periodically flexing extension 37 with the sand.

It will be noted that due to its flexibility upper valve seat 18 can also be moved relative to diaphragm 28 by applying pressure with the hand to the shoulders of extension 37 to bring the shoulder portion of extension 37 against the lower end of outlet conduit 16. Thus, an additional means is provided for keeping the inner check valve elements in perfect operating condition. For example, extraneous materials, such as snow showers moving from the cannister through the face piece, can readily be displaced when such materials collect on the inner check valve and interfere with its operation.

if desired, extension 37 can be provided with an additional layer of heat-insulating material to prevent the transfer of heat from the air within chamber 40 through the walls of extension 37 to the atmosphere. However, it has been found that when extension 37 is constructed of a material such as rubber having low thermal conductivity that it is not necessary to provide additional insulating layers down to temperatures as low as F. This is due to the fact that the portions of warm exhaled air are only held Within chamber 40 for a very short period of time before being expelled and replaced by more air from the face piece.

While various types of exhalation check valve means can be employed to control the flow of air into and out of chamber 40 it has been found that a diaphragnrtype check valve adapted to produce a substantially line contact with the valve seat in the manner illustrated in the drawing gives best results. This is undoubtedly due to the fact that the surface area of the valve seat and diaphragm which are continuously in contact with each other between exhalation intervals is comparatively small, and therefore even if the contacted surfaces freeze together it requires relatively little force to separate them. Therefore, it can be seen that the use of diaphragm valves adapted to produce a line contact between the diaphragm element and the valve seat element is advantageous when it is desired to use the mask at low temperatures, and that this particular valve structure cooperates effectively with the other elements of the protector structure of this invention to make the exhalation valves perform satisfao torily at extremely low temperatures.

Another outstanding advantage of gas masks equipped with the protector structure of this invention, as indicated above, is that they are admirably adapted for use in rubber solvent atmospheres, that is, atmospheres containing substances which tend to have a softening or solvent effect on the rubber material forming the face piece and associated structural parts. For example, atmospheres containing solvents, such as acetone, xylene, etc., tend to quickly impair the effectiveness of the protection afforded by the gas mask. Gas masks equipped with valves having thin, flexible diaphragm members (which are generally composed of rubber) are especially vulnerable, since the rubber solvents in the atmosphere will tend to rapidly impair the operation of the valve diaphragm members. In the structure of the present invention, this is guarded against by providing a chamber 40, which has heretofore been designated a warm air chamber but which can equally well be considered an In other words, chamber 40 provides a means for maintaining an atmosphere surrounding the inner diaphragm member 23 and inner valve seat 18 with an atmosphere substantially free of substances which would attack the valve and interfere with its operation, even though the exterior atmosphere contains such materials.

A still further feature of the preferred design of the gas mask protector structure as illustrated in the drawing is that it does not unduly interfere with the flow of air into and out of the face piece, that is, it does not result in even temporary rises in the internal pressure within the face piece above the pressures which are considered acceptable according to existing standards. This result is accomplished by providing a flow path for the exhausted air through the protector structure which provides minimum resistance to the flow of air. As shown more clearly in Fig. 4 of the drawing, it is preferred that the upper portion of tubular extension 37 provide downwardly extending walls designated at 41a which are located at a spaced distance from the outer periphery of inner diaphragm valve 28 and inner valve seat 18. It is also preferred that the upper portion of tubular extension 37 provide inwardly curving shoulders 41b which merge smoothly with downwardly extending wall portion 41a and are connected to conduit 16 immediately above diaphragm 29 and valve 18. As seen more clearly in Fig. 4 it will be noted that shoulder portions 41b provide an inner wall extending in a generally parallel plane to the path of flow of the air as it is expelled between inner valve seat 18 and diaphragm valve 29. Further, the rounding of the corners formed between shoulder portion 41b and upper wall portion 41a as well as between wall portion 41a and inwardly extending annular portion 44, causes the air to flow outwardly through the protector structure in winding or serpentine paths as indicated by the dotted arrowhead equipped lines in Fig. 4. In actual practice, it has been found that protector structures having the configuration illustrated in Fig. 4 give excellent results when the spacing of upper wall portion 41a is of the order of to A from the outer periphery of inner diaphragm member 28.

While in the foregoing specification an embodiment of this invention has been described in considerable detail for purpose of illustration, it will be apparent to those skilled in the art that many of the details described can be varied widely without departing from the spirit of the invention.

I claim:

1. In a gas mask adapted for use at subfreezing atmospheric temperatures, the combination comprising a face piece having an :exhalation outlet, an outward extension carried by said face piece, said extension provid ing a chamber having an outwardly-accessible flexible wall, said chamber having an inlet opening communicating with said face piece outlet and an outlet opening leading to the atmosphere so that the exhaled air passes through said chamber, inner check valve means for directing a flow of air from said face piece into said chamber, and outer check valve means including relatively movable cooperating sealing elements for directing a flow of air out of said chamber to the atmosphere, whereby portions of the warm exhaled air are held up in said chamber between periods of exhalation which therefore tend to prevent the formation of ice on said inner check valve means, said outer check valve means having at least one of said cooperating elements attached to the flexible wall of said extension, whereby said valve elements can be moved relative to each other by flexing said wall with the hand for the purpose of breaking said elements loose and freeing them of ice when their operation has been impaired by the accumulation of ice thereon.

2. In a gas mask adapted for use at low temperatures, the combination comprising a face piece having an exhalation outlet, an outward tubular extension carried by said face piece in alignment with said outlet and providing a chamber having an inlet opening communicating with said face piece outlet and an outlet opening leading to the atmosphere so that the exhaled air passes through said chamber, said tubular extension being constructed of a resilient flexible material having low thermal conductivity, inner check valve means for permitting a flow of air from said face piece into said chamber, and outer check valve means including resilient, flexible cooperating sealing elements for permitting a flow of air out of said chamber to the atmosphere, whereby portions of the Warm exhaled air are held up in said chamber between periods of exhalation which thereby tends to prevent ice from forming on said inner check valve means,

said outer check valve means having at least one of said cooperating elements attached to the inner wall of said tubular extension, whereby the attached valve element can be flexed and moved relative to the other cooperating valve element by flexing said extension with the hand for the purpose of loosening said elements when their operation has become impaired by the accumulation of ice thereon.

3. In a gas mask adapted for use at subfreezing atmospheric temperatures, the combination comprising a face piece having an exhalation outlet, an outwardlyextending tubular member carried by said face piece and providing a chamber therein having an inlet opening communicating with said face piece outlet and an outlet opening leading to the atmosphere so that the exhaled air passes through said chamber, said tubular member having resilient, flexible walls so that the portion of said tubular member surrounding said chamber can be partially collapsed by gripping said portion with the hand, inner check valve means for permitting a flow of air from said face piece into said chamber, and outer check valve means for permitting a flow of air out of said chamber to the atmosphere, said outer check valve means including a flexible, resilient diaphragm element normally resting against a valve seat element in sealing relation therewith, whereby portions of the warm exhaled air are held up in said chamber between periods of exhalation which thereby tends to prevent ice from forming on said inner check valve means, said' outer check valve means having at least one of said diaphragm and seat elements attached to the flexible walls of said tubular member, whereby said attached valve element can be flexed and moved relative to the other valve element by applying flexing pressure with the hand to said tubular member for the purpose of restoring said elements to operative condition when they have become stiffened by the accumulation of ice thereon.

4. In a gas mask adapted for use at subfreezing'temperatures, the combination comprising a face piece connected to a downwardly-extending intake conduit, an outlet conduit disposed about said intake conduit to provide an annular exhaust passage between said exhaust conduit and said intake conduit, a tubular extension carried by said exhaust conduit and providing a chamber through which the exhaled air passes to reach the atmosphere after leaving said exhaust conduit, said tubular extension having walls of a flexible, resilient material adapted to permit said walls to be partially collapsed by gripping said extension with the hand, primary check valve means controlling the flow of air from said exhaust conduit into said chamber, and secondary valve means controlling the flow of air out of said chamber to the atmosphere, said secondary valve means including an annular valve seat of flexible, resilient material carried by the walls of said extension and extending inwardly therefrom at the bottom of said chamber, and a diaphragm member of flexible, resilient material supported beneath said valve element with its periphery normally resting against said seat in sealing relation therewith, whereby said primary valve means is kept comparatively warm by the portions of exhaled air trapped within said chamber between periods of exhalation so that ice tends to form on said secondary valve means in preference to said primary valve means, while said seconday valve means can be kept in satisfactory operating condition by flexing said extension with the hand to bring about the flexing of said annular valve seat.

5. The combination of claim 4 in which said diaphragm member is provided with an upwardly-concave peripheral portion lying opposite said valve seat so that normally said diaphragm engages said valve seat with a substantially line contact.

In a gas mask adapted for use at subfreezing atmospheric temperatures, the combination comprising a face piece connected to a downwardly-extending intake conduit, an outlet conduit disposed about the upper portion of said intake conduit to provide an annular exhaust passage between said exhaust conduit and said intake conduit, said exhaust conduit being composed of a flexible, resilient material and providing an annular valve seat at the lower end thereof, a tubular extension of flexible, resilient material disposed about the lower portion of said exhaust conduit and extending downwardly about said intake conduit so that exhaled air must pass from said exhaust conduit through said tubular extension to reach the atmosphere, a diaphragm exhaust valve of flexible, resilient material carried by said intake conduit and extending thereabout adjacent said annular valve seat for cooperating therewith to provide a primary check valve, and a secondary check valve within said tubular extension below said primary check valve, said secondary check valve including an annular valve seat of flexible, resilient material carried by said tubular extension and extending inwardly therefrom toward said intake conduit, and a diaphragm valve of. flexible, resilient material carried: by said intake conduit and extending thereabout immediately below said second-mentioned annular valve seat and normally resting thereagainst' to provide a dead air space within said extension between said primary and secondary valves, whereby said primary valve is kept comparatively warm by the exhaled air trapped between said primary and secondary valves during periods of non-exhalation, while both of said annular valve seats can be flexed by gripping said extension with the hand and applying flexing pressure thereto for the purpose of keeping said primary and secondary valves in satisfactory operating condition under conditions tending to cause ice to accumulate thereon.

7. The combination of claim 6 in which in addition the upper portion of said tubular extension provides downwardly extending walls at a spaced distance from the inner diaphragm valve and annular valve seat forming said primary check valve, said upper portion of the tubular extension also providing shoulder portions ex tending inwardly and connected to said exhaust conduit immediately above said primary check valve,v said shoulder portions providing an inner wall disposed in a general parallel plane to the path of flow of air as it is expelled through said primary check valve and outwardly merging smoothly with said downwardly extending walls, whereby the path of air flow through said tubular extension is controlled to minimize the resistance to the fiow of air therethrough.

8. In a gas mask adapted for use at subfreezing atmospheric temperatures and also for use in rubber solvent atmospheres, the combination comprising a face piece connected to a downwardly extending intake con duit, an outlet conduit disposed about the upper portion of said intake conduit. to provide an annular exhaust that exhaled air must pass passage-between said exha st conduit and said intake on uit, a tubular extension of flexible, resilient material disposed about the lower portion of said exhaust conduit and extending downwardly about said intake conduit so from said exhaust conduit through said tubular extension to reach the atmosphere, inner primary check valve means for controlling the flow of air from said outlet conduit into said tubular extension, and a secondary check valve within said tubular extension below said primary check valve means, said secondary check valve including an annular valve seat of flexible, resilient material carried by said tubular extension and extending inwardly therefrom towards said intake conduit and a diaphragm valve of flexible, resilient material carried by said intake conduit and extending thereabout immediately below said second mentioned annular valve seat and normally resting thereagainst to provide a dead air space within said extension between said primary and secondary valves, whereby said primary valve is kept comparatively warm by the exhaled air trapped between said primary and secondary valves during periods of non-exhalation, while both of said annular valve seats can be flexed by gripping said extension with the hand and applying flexing pressure thereto for the purpose of keeping said primary and secondary valves in satisfactory operating condition under conditions tending to cause ice to accumulate thereon.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 428,611 Hurd May 27, 1890 2,581,007 Douglas Jan. 1, 1952 2,619,085 Bradley Nov. 25, 1952 

